Quinolines, an important class of potentially bioactive compounds, have been synthesized by treatment of O-aminoarylketones and carbonyl compounds utilizing niobium (V) chloride / polyethylenglycole(NbCl5.PEG) and niobium(V)chloride (NbCl5) as available and inexpensive catalysts. The quinoline derivatives were prepared in glycerol, an excellent solvent in terms of environmental impact, with high yields (76-98%) and short reaction times (15- 90 min). Not only diketones but also ketones afforded the desired products in good to excellent yields. The reaction time of 2-amino-5-chlorobenzophenone and dicarbonyl compounds was longer than those of 2-aminobenzophenone. The reaction of cyclic diketones took place faster than open chain analogues. These reactions also proceeded with acetophenone derivatives. In these cases the reaction times are longer.